Selection of Suture Material
Years of technical research and adaptations have resulted in advancements in suture material. Modern day suture materials have impressive mechanical and physical properties. There are many kinds of suture materials are available in the market with different properties suitable for various uses, organs or tissues. Sutures vary in terms of the size/thickness, absorbability, length, material, content and consistency.
Suture material now not only support wound edges during healing but they offer benefits like antimicrobial properties, knotless devices with uni or bidirectional barbed sutures. Replacement of skin sutures with staples, self tightening sutures, tissue adhesives and other closure devices are in the trend.
Selection of suture material depends on the properties of suture material, local standard practice, economics, procedure and personal preference (surgeon’s choice) / experience mainly. Controllable factors like perfection of technique, gentle handling of tissue and appropriate selection of suture material/pattern also plays an important role in favourable outcome. It is important to select right suture material.
“The best suture for a given laceration is the smallest diameter suture, which will adequately counteract static and dynamic tension forces on the skin.” – Brian Lin
How to select a perfect suture material?
As per the suture properties no suture meets all the criteria in all situations. One has to choose the most appropriate suture material from the large variety available based on the following selection criteria:
Selection Criteria:
- Surgical technique /Surgical procedure (Tissue / Organ being sutured)
- Disease and patient’s condition,
- Wound size (volume of tissue), wound tensile strength and Condition
- Properties of available suture material (mechanical and physical)
- Duration of immobilization (Time required for healing & potential for bacterial contamination)
- Surgical experience / Surgeon’s Choice / Personal Preference
1. Surgical technique /Surgical procedure (Tissue / Organ being sutured)
Selection of suture material depends on the surgical procedures where they are being employed. Like in surgeries of the urinary or biliary tract should be taken to avoid multifilament suture material or suture material with prolonged absorption profile/ non-absorbable sutures or any other suture with salt solution, to prevent calculus formation. Like use of catgut in urinary tract surgeries is a poor choice and gets absorbed rapidly in case of urinary tract infections or bacterial presence. Polyglycolic acid (Dexon, Truglyde, Megasorb, Petcryl) sutures also gets dissolved faster in alkaline pH of urinary tract this makes them unsuitable for cystorraphy or cystotomy closures.
Visibility is important during surgical procedure and removal of suture materials if needed. In cosmetic surgeries lighter coloured sutures are used for subcutaneous closure in the dermis because a darker colour could potentially be seen through the skin. Darker coloured non-absorbable sutures are preferred for the epidermal closure because their visibility aids in later removal. As shaving of hairs during preparation of surgical site increases the chances of infection, in the areas of dark hairs where use of blue suture will be more suitable than black for easy identification during removal.
Prolene suture have one more advantage of its color i.e. blue which is easier to identify during removal in fair coloured patients or hairy areas. Polyester suture material is good alternative for silk due to its better strength and integrity. Braided polyester sutures are the strongest synthetic sutures (except metallic).
Non-absorbable suture material is required where long term immobilization of tissues or parts is necessary e.g. retention of prosthesis or when tissues apposed are subjected to movements and heal slowly e.g. tendons, ligaments and bones.
To minimize the erythema and induration during absorption process; subcuticular sutures should be placed as deeply as possible. Epidermal closures can be performed using absorbable suture material where suture removal is not possible or difficult.
2. Disease and patient’s condition
Patient conditions like age, weight and health status plays an important role in the selection of suture material. Protein based suture materials like catgut may be inappropriate in patients suffering from conditions which may delay wound healing e.g., patient that are elder, malnourished or debilated. In these conditions suture material having long absorption profile or the use of supplemental non-absorbable suture should be considered. During the closure of the abdomen, chest, joints or other sites subjects to expansion or requiring additional support.
In cases where suture removal is difficult viz. Oral cavity, aggressive pets, Wild life pets, patients with poor follow-ups and paediatric patients in human practice, absorbable suture materials are preferred.
3. Wound size (volume of tissue), wound tensile strength and Condition
For the management of contaminated or infected wounds acceptable surgical practice should be followed. In suturing of contaminated/infected wounds use of multifilament suture material will increase the risk of harbouring bacteria and debris within the interstices in comparison to monofilament sutures. Monofilament sutures are smoother, have less tissue drag and do not adhere like multifilament sutures (eg. If infection is already there or tissue is contaminated/inflamed then polypropylene or prolene serves best because it does not adhere to the tissue and less reactive than nylon. And it is the least reactive suture material). Consideration should be taken in the use of absorbable sutures in tissues with poor blood supply as suture extrusion and delayed absorption may occur.
Suture holding power of tissues – The suture holding power of tissue depends on the kind of tissue, its density, direction in which the sutures are applied and the distance between the sutures. Among the soft tissues, skin and fascia have the maximum and the fat minimum suture holding power. The holding power of muscle depends on the direction of the application of sutures, either across or parallel to its fibers. The sutures should be applied at an optimum distance to bring about proper apposition of the wound edges without affecting the holding power of tissues. The skin sutures are usually applied 1.5 cm apart in large animals and 0.75 cm in small animals. The distance in sutures depends upon the tissue/organ to be sutured.
For ligation of small blood vessels suture material of smaller size will be preferable like 3-0 or 4-0 while large vessels will require a thicker suture material. A number of suture materials are available and selection of the material is determined by its physical and biological properties, condition of the wound and healing characteristics of the tissues to be apposed. The suture material should have tensile strength corresponding to the tissue where it is used. If the material loses its tensile strength with time, the rate at which the wound acquires strength should be considered while selecting the same. Anatomical locations are important factor in determining the amount of tension on a wound. Wounds with higher tension will require a thicker or larger gauze suture material to counter the force. Deep layers closure will reduce the wound tension. As all suture materials are alien to the body, the tissue reaction to the material should also be taken into consideration because it can modify the course of wound healing.
A wound with lower tension and appropriate size suture material gives a better cosmetic outcome.
4. Properties of available suture material (mechanical and physical)
Amount of tissue reaction that it stimulated should be minimum for any selected suture material. Tensile strength, knot security, ease of handling and unique properties of that material should be kept in mind. Suture material with inadequate tensile strength may break and result into opening of wound prior to complete healing. Monofilament suture like Nylon or high suture memory will require extra throws to secure a knot. But Nylon is preferred over prolene or polypropylene sutures due to its lower cost and easier handling. Suture with larger gauze size have poor knot security and causes more foreign body response. The smallest suture which can adequately accomplish the work at hand is the best suture for the procedure. Recent advancement like barbed suture materials are knotless secure devices.
All materials have advantages and disadvantages. Selection must be guided by careful evaluation of any wound prior to repair along with understanding of the properties of a given suture material. It helps guide rational selection for a particular application.
Selection of the needle type is also an important part while selecting a suture material. Suture for internal organs are preferred with atraumatic needles while for skin are preferred with traumatic or cutting needles. When handling any suture material care should be taken to avoid damage from handling.
5. Duration of immobilization (Time required for healing & potential for bacterial contamination)
Skin sutures which remain in place longer than 7 days during healing period may cause localized irritation and should be snipped off or removed as indicated. Normally the skin sutures are removed within 30 days (7 to 10 days usually) depending on wound condition.
In areas of high tension or avascular areas suture needs to retain its tensile strength for long period of time. Where longer duration of immobilization is required, non-absorbable monofilament sutures are preferred.
6. Surgical experience / Surgeon’s Choice / Personal Preference-
Personal preference, availability and economical aspect are deciding factor in selection of suture material. A surgeon needs to be familiar with the important characteristics of the suture which going to be selected for the procedure. Suture will be either absorbable or nonabsorbable. In case of absorbable suture material, rate of absorption is important factor. Selection of monofilament and multifilament (braided/twisted) suture also depends on the surgeon’s choice when both can be deployed.
It is recommended to use one size larger for continuous suture pattern than the interrupted suture pattern when closing linea alba or rectus.
Conculsion:
Properties of suture material, patient factors, wound conditions, procedure and surgeons preference are important factors but aftercare and management also play important role in favourable outcomes.